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Hard water and soft water

Why your pipes might prefer soft water

Hard and soft water 

What are hard and soft water?

When minerals like magnesium and calcium build-up in the water supply to a certain level, the result is known as hard water. Soft water, such as rainwater, is just water that contains less of these minerals. Hardness in water occurs naturally - for example, when water picks up mineral content while flowing over rocks on the way to the reservoir. It’s also very common. Around 60% of homes in the UK will most likely have hard water in the taps.

You can tell hard water from soft water in two main ways. Firstly, it’s bit harder to make a soap lather with hard water than it is with soft water. Secondly, the minerals in hard water tend to clump together to form limescale.

How does hard water affect my pipes?

Perhaps the most notable effect of hard water is limescale, that tough, chalky layer sometimes seen at the bottom of kettles. The pipes in your heating system and your boiler are also vulnerable to limescale build-up, and this can lead to problems.  Limescale makes it more difficult for water to flow through pipes and the chalky lining also makes them harder to heat. As a result, your heating system becomes less efficient overall, leading to an increased possibility of boiler problems - not to mention higher energy bills.

Can I soften my water?

There are a number of steps you can take to reduce the effects of hard water, such as using a water softener. These gadgets work by drawing out some of the minerals that lead to hard water and replacing them with sodium. You should know, however, the extra sodium means the softened water shouldn’t be used as drinking water. You’ll have to set up a separate supply for drinking if you do use a water softener. All water softeners must be fitted in accordance with water regulations.

Given how common hard water is, there’s a wide array of chemical softeners available. Which? doesn’t test chemical water softeners as it says they ‘work with little variation’. The consumer site also says it doesn’t test electromagnetic water softeners, as there isn’t any consistent scientific evidence that they work.

Other ways you can minimise the effects of water include:

  • Boiling water. This could provide you with water for drinking or cooking, although boiling only works for so-called ‘temporary’ hardness. This differs chemically from ‘permanent’ hardness, which is what a chemical water softener tackles.
  • Keeping the temperature of your water to 60oC or lower to decrease limescale build-up.
  • Using a wire mesh scale collector in your kettle to minimise limescale deposits.
  • Finding out if you’re in one of the UK’s hard water areas. Water hardness does vary around the country, roughly on a North/South basis. Your water supplier will probably have a postcode checker on their website that can identify hard or soft water areas.

What should I do if I suspect my boiler is affected by hard water?

 If a build-up of limescale is forcing your boiler to work harder, it could make itself known via a noise known as kettling. You can read more about kettling and noisy boilers here. We’ve also put together some advice on diagnosing boiler trouble, because it may well be that you have nothing to worry about. If you do have a persistent problem with your boiler, however, it could be time to call in an engineer.

To protect your boiler in the future, you may want to consider boiler cover, with options for emergency boiler repair and maintenance. Depending on any current problems you have with your boiler, you may have to make some repairs before cover starts. 

For a broad introduction to domestic heating systems, try our Big Boiler Handbook, which you can download for free.

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